Here are a few things you can do to secure your web server:
Perform regular maintenance on your account. Remove things that are no longer used or needed such as; FTP accounts, third party applications, unused email accounts, old databases, and scripts. This will free up some disk space also keep things organised, and decreases attacker exploiting unsecured areas old or of your account.
Change your passwords on regular basis
Update all your passwords regularly.
use .htaccess to secure non-public areas of your website
.htaccess will enable you to specify user credentials for accessing a page or directory.
Review file and folder permissions
Incorrect file and folder permissions is a big compromise on a shared hosting account.